Apparatus for picking up an auxiliary stack when conveying sheets in a printing machine

ABSTRACT

An apparatus for picking up an auxiliary stack when conveying sheets in a printing machine that makes it possible to reduce constraining forces when guiding loadbearing elements. The apparatus has loadbearing elements disposed on a crossmember for the auxiliary stack, the loadbearing elements being fastened to the crossmember so as to pivot in at least two degrees of freedom.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an apparatus for picking up an auxiliary stackwhen conveying sheets in a printing machine.

German Patent DE 41 29 164 C1, corresponding to U.S. Pat. No. 5,242,261to Pollich et al., describes a device for combining a residual sheetstack and a main sheet stack in the feeder of a sheet-fed printingpress. The device includes a load bearing plate for the residual sheetstack, which has rectangular grooves on its upper side. Rigid, straight,rectangular rods are provided at the spacing of the grooves for thetemporary support of the residual stack. The rods are fastened rigidlyto a crossmember.

German Published, Non-Prosecuted Patent Application DE 197 38 029 A1contains a sheet feeder for a printing press, having an auxiliarystacking table in which rods are provided that are disposed parallel toone another and can be inserted into the plane of a stack. In a firstembodiment, resilient mounting of the rods in the form of a flexiblecrossmember is provided.

The resilient mounting has the effect that there is a difference intravel between the rods when the auxiliary stacking table is pulled outof the sheet feeder. In a further embodiment, one part of the rods isfastened fixedly to a crossmember while another part of the rods isassociated with the crossmember through springs. Each spring isassociated with a rod guide in which a rod can slide in the longitudinaldirection.

The crossmember is moved with a drive to insert the rods into thegrooves. Here, there are stringent requirements placed on the dimensionsand spacings of the grooves and rods and on the positioning system forthe crossmember. In order for it to be possible to guide the rods asfreely as possible in the grooves, it is necessary to expend largeamounts on costs and material.

In the stacking table with a device for refreshing a stack duringcontinuous operation of a sheet-processing machine according to GermanPublished, Non-Prosecuted Patent Application DE 42 15 791 A1,self-supporting chains are used as deposition elements for an auxiliarystack. The chains are seated on chain sprockets in a parallelconfiguration. To insert the chain ends into the grooves of a stackboard, a motor that acts on the chain sprockets is provided and guideplates and tubular pieces to guide the chains. The mobility of thechains is defined by the geometry of the chain sprockets and chainlinks.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide an apparatus forpicking up an auxiliary stack when conveying sheets in a printingmachine that overcomes the hereinafore-mentioned disadvantages of theheretofore-known devices of this general type and that makes it possibleto reduce constraining forces when guiding loadbearing elements.

With the foregoing and other objects in view, there is provided, inaccordance with the invention, an apparatus for picking up an auxiliarystack when conveying sheets in a printing machine, including acrossmember and loadbearing elements being disposed at the crossmemberfor picking up the auxiliary stack, the loadbearing elements beingfastened movably to the crossmember to pivot in at least two degrees offreedom.

In accordance with another feature of the invention, there is provided achain mechanism, the crossmember having two sides and being coupled tothe chain mechanism on both of the two sides, and the loadbearingelements being members pivotably connected to the crossmember.

In accordance with a further feature of the invention, the invention canbe applied particularly advantageously in apparatuses in which pivotablyconnected members that can be moved on a curved path are used asloadbearing elements.

In accordance with an added feature of the invention, the apparatustakes up a small amount of volume in such a variant. The ends of theloadbearing elements can be fastened in cutouts in the crossmemberthrough joints.

In accordance with an additional feature of the invention, the at leastone joint movably connects the at least one loadbearing element to thecrossmember.

In accordance with yet another feature of the invention, the walls of acutout can simultaneously form stops for the movement of a loadbearingelement.

In accordance with yet a further feature of the invention, in order forit to be possible to operate with constraining forces that are as low aspossible, a loadbearing element can be coupled to a crossmember througha joint that permits movement in four degrees of freedom. In particular,a universal joint can be provided between the crossmember and aloadbearing element.

If, for supporting a stack, a pallet is used that has grooves in whichthe loadbearing elements are positioned, the loadbearing elements can bedisposed in the crossmember so as to be displaceable within limits inthe direction of the movement out of the grooves. Here, pairs of theloadbearing elements can have different limit regions for thedisplacement.

With the objects of the invention in view, there is also provided anapparatus for picking up an auxiliary stack when conveying sheets in aprinting machine, including a crossmember moving on a curved path andhaving cutouts, loadbearing elements being disposed at the crossmemberfor picking up the auxiliary stack, and at least one joint beingdisposed in at least one of the cutouts between the crossmember and atleast one of the loadbearing elements and movably connecting the atleast one loadbearing element to the crossmember in at least two degreesof freedom.

With the objects of the invention in view, there is also provided anapparatus for picking up an auxiliary stack when conveying sheets in aprinting machine, including a guide to be disposed adjacent a locationfor the auxiliary stack in the printing machine, a crossmember movablydisposed at the guide, and loadbearing elements disposed at thecrossmember for moving the auxiliary stack, the loadbearing elementsbeing operatively connected to the crossmember to pivot in at least twodegrees of freedom.

With the objects of the invention in view, in a printing machine havingan auxiliary stack holding sheets, there is also provided an apparatusfor picking up the auxiliary stack when conveying the sheets including acrossmember and loadbearing elements disposed at the crossmember forpicking up the auxiliary stack, the loadbearing elements being fastenedmovably to the crossmember to pivot in at least two degrees of freedom.

Other features that are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin an apparatus for picking up an auxiliary stack when conveying sheetsin a printing machine, it is, nevertheless, not intended to be limitedto the details shown because various modifications and structuralchanges may be made therein without departing from the spirit of theinvention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof, will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, cross-sectional view of a feeder of a sheet-fedprinting press according to the invention;

FIG. 2 is a partially hidden and perspective view of loadbearingelements according to the invention fastened to a crossmember;

FIG. 3 is a fragmentary, cross-sectional view of loadbearing elementsinserted into grooves in a pallet according to the invention;

FIG. 4 is a fragmentary, cross-sectional view of a guide for acrossmember for loadbearing elements;

FIG. 5 is a fragmentary, cross-sectional view of the guide of FIG. 4along section lien V-V;

FIG. 6 is a fragmentary, cross-sectional view of joints according to theinvention for attaching loadbearing elements to a crossmember;

FIG. 7 is a fragmentary, cross-sectional view of the joints of FIG. 6but rotated one-quarter turn; and

FIG. 8 is a fragmentary, cross-sectional view of an attachment ofloadbearing elements according to the invention with axial play.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawings in detail and first,particularly to FIG. 1 thereof, there is shown a feeder 1 and a firstprinting unit 2 of a sheet-fed offset printing press. The printing unit2 includes an inking unit 3, a dampening unit 4, a form cylinder 5, atransport cylinder 6, an impression cylinder 7, a feed cylinder 8, and atransfer drum 9. A pallet 10 on which a stack 11 is situated belongs tothe feeder 1. The pallet 10 lies on a stacking table 12 that can bepositioned in the vertical direction 15 with the aid of chains 13, 14 ofa chain mechanism. To make it possible to refresh the stack 11 duringcontinuous operation of the sheet-fed offset printing press, anauxiliary stack apparatus is provided. The auxiliary stack apparatusincludes a holder 16 for a plurality of loadbearing elements 17 disposedin parallel, an advancing device 18, and a guide 19 for the loadbearingelements 17, and a front loadbearing rail 20. The holder 16 can bepositioned in the vertical direction by chains 21 of a chain mechanismtogether with the guide 19 and the advancing device 18, and can bepositioned in the horizontal direction perpendicularly with respect tothe plane of the drawing of FIG. 1 by a non-illustrated positioningapparatus. The loadbearing rail 20 can be positioned in the verticaldirection 15 by chains 22 of a chain mechanism. The pallet 10 has websand grooves. The stack 11 lies on the webs of the pallet 10. Theloadbearing elements 17 can be positioned through the grooves by theadvancing device to such an extent that they rest on the loadbearingrail 20.

During printing, the stack 11 is guided against a suction head 23 havingsuction grippers 24, 25, using the chains 13, 14 in accordance with theprinting velocity. Vacuum lines 26 lead to the suction grippers 24, 25.The suction head 23 can be moved to and fro in the horizontal direction27. The sheets 28 that lie on top of the stack 11 are separated usingthe suction grippers 24, 25 and are conveyed onto a feed table 29against front lays 30 by the movement of the suction head 23. The sheets28 are transferred from the front lays 30 to the feed cylinder 8 by aswinging gripper 31. The sheet 28 is printed as it passes through thenip between the impression cylinder 7 and the transfer cylinder 6. Thetransport drum 9 transports the sheet 28 to further printing units.

In the height position shown in FIG. 1 of the stacking table 12, theinstant for refreshing the stack 11 has been reached. To refresh thestack 11, the auxiliary stack 11 is picked up temporarily on theloadbearing elements 17 together with the remainder of the sheets 28.For such a purpose, the holder 16 with the loadbearing elements 17 ispositioned in the vertical and horizontal direction such that the tips32 of the loadbearing elements 17 point approximately toward the centersof the cross-sectional areas of the pallet grooves. Afterward, theadvancing device 18 is set in operation with a motor 33 and a mechanism34. As a result, the loadbearing elements 17 that are fastened to acrossmember 35 pass through the pallet grooves onto the loadbearing rail20. The loadbearing elements 17 are of pivotably connected members 36that follow the curved shape of the guide 19 outside the pallet groovesand a guide in the holder 16. After passing through the guide in theholder 16 and after lying on the loadbearing rail 20, the members of theloadbearing elements 17 are flexurally rigid for the load of theauxiliary stack 11. Furthermore, the auxiliary stack 11 is moved towardthe suction grippers 24, 25 by vertical driving of the holder 16 and theloadbearing rail 20 through the chain mechanism on the chains 21, 22.Here, the weight of the auxiliary stack 11 is completely held on theloadbearing elements 17. While the auxiliary stack is moved toward thesuction head 23 by the chains 21, 22, the stacking table 12 togetherwith the pallet 10 is lowered on the chains 13, 14 through the chainmechanisms until it assumes a lower position for picking up a new mainstack. The new main stack is moved under the loadbearing elements 17 ofthe auxiliary stack even before the auxiliary stack 11 has beenprocessed. As a result, the main stack and the auxiliary stack 11 arealigned. Subsequently, the loadbearing elements 17 are drawn in in thedirection of the guide 19 by the advancing device 18. As a result, theauxiliary stack 11 and the new main stack are combined to form a stack11. The combined stack 11 is moved further toward the suction head 23 bythe chain mechanism and the chains 13, 14.

If designations that have already been introduced are used in thefollowing description, then they are, in each case, features having theequivalent function.

FIG. 2 shows the loadbearing elements 17 on the crossmember 35. Thecrossmember 35 has cutouts 37 in which the ends of the loadbearingelements 17 are fastened. The loadbearing elements 17 are inserted inelongate form into grooves 38 of the pallet 10, which is shown ingreater detail in FIG. 3. Both the tips 32 of the loadbearing elements17 and the grooves 38 have insertion bevels 39, 40.

FIGS. 4 and 5 show two views with details of how the crossmember 35 isdisposed in the guide 19. The crossmember 35 is guided on a roller track43 on both sides by rollers 41, 42. To move the crossmember 35 forwardand backward in the guide 19, the crossmember 35 is coupled to chains46, 47 through pins 44, 45. The chains 46, 47 slide in the guide 19 andare connected to the mechanism 34.

FIGS. 6 and 7 show an articulated connection of a loadbearing element 17to the crossmember 35. Universal joints 48 are disposed in the cutouts37 of the crossmember 35. The end of the loadbearing element 17 ismounted so as to pivot about the axis of a pin 49. The pin 49 is seatedon one side of a connecting piece 50 that is in the shape of a doublefork. A bolt 55 whose axis runs parallel to the axis of the pin 49 isprovided on the other side of the connecting piece 50. A further pin 51penetrates the bolt 55 in a direction that is perpendicular with respectto the axis of the pin 49. Furthermore, the pin 51 is held in a bolt 52with fork-shaped ends. The cylindrical bolt 52 is rotatably mounted in ahole in the crossmember 35. A projection 53 of the bolt 52 and asecuring ring 54 prevent the bolt 52 from being displaced in the axialdirection. The loadbearing element 17 and the connecting piece 50 can bepivoted about the axis of the pin 51. The pivoting movement of theloadbearing element 17 about the axes of the pins 49, 51 and therotation about the axis of the bolts 52, 55 are limited by the innerwalls of the cutouts 37.

When the loadbearing elements 17 are inserted into the grooves 38 of thepallet 10 (see FIG. 3), excessively high constraining forces on theloadbearing elements 17 and the pallet 10 are avoided because, even inthe event of slight constraining forces, the loadbearing elements 17yield to the resistance. In other words, a movement of the loadbearingelements 17 takes place in the context of the degrees of freedom presentas a result of the joints 48 and the wall of the cutouts 37.

FIG. 8 shows an embodiment in which some of the loadbearing elements 17have an amount of play x in the crossmember 35 because the length of thebolt 52 has been somewhat enlarged in comparison with FIGS. 6 and 7.When the loadbearing elements 17 under the stack 11 are pulled out,loadbearing elements 17 having the amount of play x begin to be pulledout somewhat later than loadbearing elements 17 without play. As aresult of a different amount of play x, every loadbearing element 17 canbe pulled out at a different instant. The play x can be provided inequal amounts symmetrically with respect to the sheet center across thewidth of a sheet 28, in the case of pairs of loadbearing elements 17.

This application claims the priority, under 35 U.S.C. § 119, of Germanpatent application No. 103 58 741.1, filed Dec. 4, 2003; the entiredisclosure of the prior application is herewith incorporated byreference.

1. An apparatus for picking up an auxiliary stack when conveying sheetsin a printing machine, comprising: a crossmember; and loadbearingelements being disposed at said crossmember for picking up the auxiliarystack, said loadbearing elements being fastened movably to saidcrossmember to pivot in at least two degrees of freedom.
 2. Theapparatus according to claim 1, further comprising: a chain mechanism;said crossmember having two sides and being coupled to said chainmechanism on both of said two sides; and said loadbearing elements beingmembers pivotably connected to said crossmember.
 3. The apparatusaccording to claim 1, wherein said crossmember is moved on a curvedpath.
 4. The apparatus according to claim 1, further comprising a curvedpath and said crossmember moving on said curved path.
 5. The apparatusaccording to claim 1, wherein: said crossmember has cutouts; and atleast one joint is disposed in at least one of said cutouts between saidcrossmember and at least one of said loadbearing elements.
 6. Theapparatus according to claim 1, wherein: said crossmember has cutouts;and joints are disposed in said cutouts between said crossmember andeach of said loadbearing elements.
 7. The apparatus according to claim5, wherein said at least one joint movably connects said at least oneloadbearing element to said crossmember.
 8. The apparatus according toclaim 6, wherein said joints movably connect said loadbearing elementsto said crossmember.
 9. The apparatus according to claim 5, wherein saidcutouts have walls forming stops for movement of said at least oneloadbearing element.
 10. The apparatus according to claim 6, whereinsaid cutouts have walls forming stops for movement of a respective oneof said loadbearing elements.
 11. The apparatus according to claim 7,wherein said at least one joint provides four degrees of freedom forsaid at least one loadbearing element.
 12. The apparatus according toclaim 8, wherein said joints provide four degrees of freedom for saidloadbearing elements.
 13. The apparatus according to claim 1, furthercomprising a universal joint disposed between said crossmember and atleast one of said loadbearing elements.
 14. The apparatus according toclaim 1, further comprising universal joints disposed between saidcrossmember and said loadbearing elements.
 15. The apparatus accordingto claim 1, wherein: the auxiliary stack to be picked up lies on apallet; the pallet has grooves in which said loadbearing elements are tobe disposed; and said loadbearing elements are disposed displaceably insaid crossmember within given limits in a direction of movement out ofthe grooves.
 16. The apparatus according to claim 15, wherein givenpairs of said loadbearing elements have different regions of limit forthe displacement.
 17. The apparatus according to claim 15, wherein atleast one pair of said loadbearing elements have different regions oflimit for the displacement than other of said loadbearing elements. 18.An apparatus for picking up an auxiliary stack when conveying sheets ina printing machine, comprising: a crossmember moving on a curved pathand having cutouts; loadbearing elements being disposed at saidcrossmember for picking up the auxiliary stack; and at least one joint:being disposed in at least one of said cutouts between said crossmemberand at least one of said loadbearing elements; and movably connectingsaid at least one loadbearing element to said crossmember in at leasttwo degrees of freedom.
 19. The apparatus according to claim 18, whereinsaid at least one joint provides four degrees of freedom for said atleast one loadbearing element.
 20. The apparatus according to claim 18,further comprising a universal joint disposed between said crossmemberand at least one of said loadbearing elements.
 21. An apparatus forpicking up an auxiliary stack when conveying sheets in a printingmachine, comprising: a guide to be disposed adjacent a location for theauxiliary stack in the printing machine; a crossmember movably disposedat said guide; and loadbearing elements disposed at said crossmember formoving the auxiliary stack, said loadbearing elements being operativelyconnected to said crossmember to pivot in at least two degrees offreedom.
 22. In a printing machine having an auxiliary stack holdingsheets, an apparatus for picking up the auxiliary stack when conveyingthe sheets comprising: a crossmember; and loadbearing elements disposedat said crossmember for picking up the auxiliary stack, said loadbearingelements being fastened movably to said crossmember to pivot in at leasttwo degrees of freedom.